In a measuring cup mix together instant coffee and hot water until coffee has dissolved, then add buttermilk.

Alternating between flour mixture and buttermilk, mix into butter mixture until well incorporated. Once incorporated beat for another couple of minutes.

Pour batter into prepared spring form pan and bake for 50 - 60 minutes, or until an inserted toothpick comes out clean. Set to cool, once cool enough to touch run a knife along edge of cake and release from spring form pan and let cool completely on a wire rack.